How to Combine a Magnetic Thickness Tool with a Multi-Finger Caliper for Casing Inspection?

Casing integrity evaluation often requires more than one measurement method. While a multi-finger caliper can provide detailed information about internal casing geometry, deformation, and restrictions, a Magnetic Thickness Tool can help identify changes in casing wall thickness and potential metal loss. Combining these two inspection technologies can provide a more comprehensive understanding of casing condition in cased-hole wells.

For wireline service companies, well integrity engineers, and technical procurement managers, the combination of a Magnetic Thickness Tool and Multi-Finger Caliper can be considered when a casing inspection program needs both dimensional and metal-loss information.

This article explains how the two tools complement each other, what information each tool provides, and which technical specifications should be considered when sourcing an integrated casing inspection solution.

A multi-finger caliper is primarily designed to evaluate the internal geometry of casing or tubulars.

Multiple mechanical or electronic fingers contact the internal casing surface while the tool moves through the well. The recorded measurements can be processed to generate a circumferential profile of the casing.

Depending on the tool configuration, a multi-finger caliper can help identify:

◆Casing deformation

◆Ovality and eccentricity

◆Localized restrictions

◆Internal wear

◆Buckling or deformation

◆Mechanical damage

◆Changes in casing internal diameter

◆Localized geometric anomalies

A higher finger count can provide greater circumferential coverage. For example, a 40-finger caliper can provide detailed information about the casing's internal profile and help engineers characterize localized deformation more effectively.

However, a caliper primarily describes geometry. A reduction in internal diameter does not automatically indicate the amount of metal lost from the casing wall.

This is where a magnetic thickness inspection method can provide complementary information.

 

Our Multi-Finger Caliper

 

A Magnetic Thickness Tool is designed to evaluate casing wall conditions using electromagnetic or magnetic measurement principles.

Depending on the specific tool design and operating parameters, magnetic thickness inspection can provide information related to:

◆Casing wall thickness

◆Metal loss

◆Corrosion-related deterioration

◆Localized defects

◆Internal and/or external metal-loss indications

◆Multiple casing-string conditions in applicable configurations

The exact measurement capability depends on the tool's sensor configuration, casing material, casing dimensions, operating environment, and interpretation methodology.

For this reason, technical specifications should be reviewed carefully before selecting an MTT for a particular well.

 

Our factory & quipment

 

A cased-hole logging solutions provider.

The main advantage of combining the two technologies is that they measure different physical characteristics of casing condition.

The multi-finger caliper focuses on internal geometry, while the Magnetic Thickness Tool focuses on casing wall condition and metal-loss-related information.

Consider a casing section where the internal diameter has decreased.

A multi-finger caliper may identify the location and geometry of the restriction. However, additional information may be required to determine whether the anomaly is associated with deformation, wear, corrosion, or another casing condition.

When magnetic thickness measurements are available from the same inspection program, engineers can compare the dimensional information with wall-condition data.

This creates a more complete inspection workflow:

Casing Geometry → Metal-Loss Information → Data Correlation → Integrity Assessment

The two datasets should not be treated as interchangeable. Instead, they should be interpreted together according to the tool specifications and well conditions.

A practical casing inspection workflow can be divided into several stages.

1. Define the inspection objective

Before selecting tools, identify the primary concern.

For example:

◆Casing deformation

◆Corrosion

◆Metal loss

◆Internal restriction

◆Mechanical damage

◆General casing integrity screening

The inspection objective determines whether a caliper, magnetic thickness tool, or both are required.

2. Establish casing and well parameters

Engineers should confirm:

◆Casing OD and weight

◆Casing grade and material

◆Casing ID

◆Number of casing strings

◆Expected temperature and pressure

◆Well deviation

◆Fluid characteristics

◆Maximum logging speed

◆Expected defect dimensions

These parameters should be checked against the operating envelope of both tools.

3. Acquire multi-finger caliper data

The multi-finger caliper can be used to establish the internal casing geometry.

Engineers can examine changes in internal diameter and circumferential deformation and identify intervals requiring further analysis.

4. Acquire magnetic thickness data

The Magnetic Thickness Tool can then provide complementary information about casing wall condition.

Depending on the tool configuration, the inspection may help identify areas where metal loss or thickness variation requires further investigation.

5. Correlate the datasets

The most useful stage is often data correlation.

For example:

Caliper anomaly + magnetic thickness anomaly

may indicate that an interval requires detailed integrity evaluation.

In contrast, a caliper response without a corresponding magnetic thickness indication may require a different interpretation.

The final conclusion should always be based on the tool response characteristics, calibration information, well conditions, and engineering interpretation rather than on a single measurement.

When purchasing a combined casing inspection solution, procurement teams should avoid evaluating tools only by product name.

A practical RFQ should include technical requirements such as:

Multi-Finger Caliper

◆Number of fingers

◆Casing OD/ID range

◆Maximum logging temperature

◆Maximum operating pressure

◆Measurement resolution

◆Sampling rate

◆Logging speed

◆Memory capacity

◆Centralization requirements

◆Data output format

◆Calibration requirements

Magnetic Thickness Tool

◆Measurement principle

◆Applicable casing size range

◆Minimum detectable wall-thickness change

◆Measurement accuracy

◆Maximum temperature and pressure

◆Logging speed

◆Memory capacity

◆Sensor configuration

◆Single- or multi-string applicability

◆Data processing and interpretation requirements

System Compatibility

Procurement teams should also confirm:

◆Tool OD

◆Length

◆Weight

◆Battery configuration

◆Memory mode

◆Power requirements

◆Mechanical connection

◆Logging cable or wireline compatibility

◆Data download and processing software

◆Field maintenance and spare-parts availability

These details can significantly affect whether the proposed tools can be deployed efficiently in an existing wireline or cased-hole logging operation.

The combination of a Multi-Finger Caliper and Magnetic Thickness Tool can be considered when a casing inspection requires both dimensional characterization and wall-condition evaluation.

Potential applications include:

◆Casing integrity assessment

◆Corrosion investigation

◆Metal-loss evaluation

◆Deformation analysis

◆Post-workover inspection

◆Production well integrity monitoring

◆Troubleshooting unexpected restrictions

◆Pre-intervention casing evaluation

It can also be useful in wells where operators need more information before deciding on repair, intervention, or continued production strategies.

A Magnetic Thickness Tool and Multi-Finger Caliper provide complementary casing inspection information.

The multi-finger caliper focuses on internal casing geometry and deformation, while magnetic thickness inspection provides information related to casing wall condition and metal loss. Combining the datasets can help engineers build a more complete picture of casing integrity than relying on either measurement independently.

For technical procurement teams, the key is to define the casing size range, measurement requirements, pressure and temperature ratings, logging mode, data format, and compatibility requirements before requesting quotations.

For field engineers, the key is to correlate the two measurement datasets while considering tool response characteristics, calibration, well conditions, and the limitations of each measurement method.

If you are sourcing a Magnetic Thickness Tool, Multi-Finger Caliper, or combined casing inspection solution for wireline or cased-hole logging applications, provide your casing specifications and operating requirements to info@a-oneoil.com. A-One Oil can help review the application and recommend a suitable tool configuration.